Lamp base terminal welding



R. A. KUEBLER 2,892,923

LAMP BASE TERMINAL WELDING June 30, 1959 2 Sheets-Sheet 1 Filed Aug. 26, 1958 Invervtov: Robevfi: A.KL1DLT", y

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United States Patent LANIP BASE TERMINAL WELDING Robert A. Knebler, Cleveland Heights, Ohio, assignor to General Electric Company, a corporation of New York Application August 26, 1958, Serial No. 757,278

7 Claims. (Cl. 219-117) This invention relates to the basing of electric lamps and more particularly to a method and apparatus for electrically welding lead wires to the metal terminals of the lamp bases.

In the manufacture of fluorescent lamps using low voltage preheatable electrodes such as the rapid start type, it is essential to achieve a low resistance connection between the lead wires to the electrodes and the metal terminals of the lamp bases. Best results are obtained by welding the connections and this practice has largely replaced soldering. A technique and apparatus which has found extensive use in the welding of fluorescent lamp base pins is described in Patent 2,749,528Albrecht, Welded Fluorescent Lamp Base Pins. However the welding of lead wires to the terminals of recessed double contact bases has presented additional problems and it is to these that the present invention is particularly directed.

The object of the present invention is to provide a new and improved mehod for welding the lead wires of electric lamps to the metal terminals of their bases.

Another object of the invention is to provide apparatus using the method of the invention for welding lead wires to various types of metal terminals.

A more specific object of the invention is to provide an apparatus suitable for welding lead wires to the enclosed terminals of recessed double contact fluorescent lamp bases.

The practice in welding lead wires to base terminals heretofore has been to trim off the lead Wire leaving only a short stub which is melted down into the weld juncture by the welding operation. Two electrodes only have been used, one to engage the metal terminal and the other to contact initially the projecting stub in order to produce an arc at that point. In accordance with the present invention, the lead wire is not trimmed off for the welding operation but instead is bent aside from the apertured boss or protuberance in the metal terminal through which it projects. Three electrodes are used to effect the weld. A first electrode contacts the projecting portion of the lead at a point removed from the aperture through which it projects. A second electrode engages the metal terminal. Both the first and second electrodes are connected to the same side of the discharge capacitor, preferably the positive side. A third electrode which is connected to the other side of the discharge capacitor, namely the negative side, is moved down into engagement with the lead wire and initially contacts it immediately above the apertured boss. The current from the third electrode divides, part flowing through the projecting lead portion to the first electrode and causing the lead portion to melt and; fuse away from the aperture. The other part of the current, and the remaining discharge after the projecting lead portion has been fused back, flows through the metal terminal and the retained part of the lead wire to the second electrode and causes the lead wire and the apertured boss to melt and fuse together in a welded junction.

In a preferred apparatus for carrying out the method of the invention in welding lead wires to the enclosed terminals of a recessed double contact base, a welding mechanism is provided adapted to operate in conjunction with the usual lamp finishing machine or basing reel. The welding mechanism advances a first electrode into engagement with the bent-over portion of the lead, a second electrode into engagement with the metal terminal within the cavity in the projecting boss of he base, and a third electrode into engagement with the lead immediately at the apertured boss through which it projects. A capacitor bank is discharged to eiiect the weld, the positive side of the capacitors being connected to the first and second electrodes and the negative side to the third electrode.

For further objects and advantages and for a better understanding of the novel features of the invention, attention is now directed to the following description and accompanying drawing. The features of the invention believed to be novel will be more particularly pointed out in the appended claims.

In the drawing:

Fig. 1 is a front elevation of a welder for a recessed double contact base mounted on a lamp finishing machine.

Fig. 2 is a side elevation of the welder of Fig. 1.

Fig. 3 is an enlarged detail of the welder of Fig. 1 showing the initial engagement of the electrodes with the base.

Fig. 4 is a similar detail View showing the completed weld.

Fig. 5 is a front elevation of a welding mechanism forming a variant of the invention and particularly adapted for welding large single pin fluorescent lamp bases.

Fig. 6 is a side elevation of the welding mechanism of Fig. 5.

Referring to Figs. 1 to 4 of the drawings, there is shown a welding mechanism in accordance with the invention specifically adapted to welding the lamp leads to the en closed terminal strips of recessed double contact bases. Such bases are described and claimed in copending application Serial No. 643,430, filed March 1, 1957, of Anton M. Krupp et al., entitled Recessed Double Contact Strip Base, and assigned to the same assignee as the present invention. They are used commercially with certain high current types of fluorescent lamps generally designated high output rapid start and Power Groove. These lamps have low voltage preheating current continuously applied to the electrodes and for this reason it is particularly important that low resistance connections of the lead wires to the base terminals be achieved.

The fluorescent lamp 1, of which the upper end only is shown in the drawings, is supported vertically on a rotary turret type finishing machine or basing reel 2. A recessed double contact base 3 cemented on the upper end of the lamp is accommodated in an inverted cupshaped receptacle or basing head 4 fastened to the upper rotating plate or turret 5 of the basing reel. The basing head is centrally apertured to allow the plastic web or embossment 6 of the base to project upwardly therethrough. The turret of the basing reel is indexed periodically in the usual fashion and the various operations of basing the lamp including the lead welding here in question are performed during the dwell intervals of the heads at appropriate stations. The drawings show lamp 1 during the dwell interval at the first Welding station.

As shown in Figs. 3 and 4, the plastic embossment 6 of the base is hollow and has a central passage whose internal side walls are lined with contact strip terminals 7, 7'. The laterally extending upper portions of the strip terminals which are bent over at right angles to the vertical portions are provided with apertured bosses 8, 8' positioned over wiring passages 9, 9' in the internal side walls of the plastic embossment 6. The lead wires 11, '11" extend upwardly through the wiring passages and pass out through the wiring passages and pass out through the apertured bosses S, S. The function of the weld ing mechanism is to sever the portions of the lead wires projecting beyond the apertured bosses, and to weld the lead wires to the strip terminals at the bosses, simultaneously closing the apertures.

The welding mechanism comprises a vertically reciprocable electrode holder or block 12 depending from a slidable rod 13 fastened to the actuating rod 14 of a pneumatic air cylinder 15. The mechanism is supported on an L-shaped bracket 16 bolted to an inclined standard 17 which in turn is fastened to the frame 18 of the has ing reel. A group of four rods 19 to 22 rising from bracket 16 support a plate 23 to which the air cylinder is attached. When air is admitted to the cylinder, its actuating rod 14 drives slidable rod 13 downwards through a long bushing 24 fastened to bracket 16. An adjustable bolt 25 and lock nut 26 at the upper end of rod 13 determine the point of engagement of the actuating rod 14 at the upper limit of movement. A collar 27 on rod 13 engages a pair of studs 28 to determine the downward limit of movement. A helical spring 29 compressed between collar 27 and the shoulder of bushing 24 returns rod 13 to its upper limit when air is released from the cylinder.

The electrode holder or block 12 is made of an insulating material such as a block of laminated phenolic plastic. It is supported on the lower end of slidable rod 13 by means of a block 31 threaded on the lower end of the rod and an L-shaped bracket 32 accommodated in ways formed at 33 in the lower face of the block. The ways 33 permit forward and backward adjustment of the electrode block in a radial direction relative to the basing reel and the knurled screw 34 is used to lock the block in place.

The first electrode for contacting the projecting portion 11a of lead 11 comprises a grooved blade 35 on the lower end of a rod 36 biased downwardly by a spring 37 and retained by a pin 38. The second electrode for contacting strip terminal 7 comprises a pin 39 fastened to an inclined rod 41 biased downwardly by a spring 42 and retained in the holder by a pin 43. A notch at 44 in pin 39 assures clearance for the boss 8' of the other strip terminal of the base. The third electrode which engages the lead wire 11a immediately above the apertured boss 8 of the terminal strip is a slender rod 45 fixedly mounted relative to the electrode holder, though with provision for adjustment on account of wear as a result of arcing at the tip. The connections to the various electrodes are made through retaining pins 38 and 43 in the case of conductors 46 and 47, and through locking pin 48 in the case of conductor 49 to the third electrode. The first and second electrodes are connected to the positive side of capacitor bank 51 through current regulating rheostats 52, 53 respectively. The capacitor bank is charged with the polarity indicated through a conventional charging circuit 54 energized at terminals 55 from the usual 115 volt, 60 cycle A.C. supply.

The welding mechanism carries out the welding process of the invention in the following fashion. Lamp 1 accommodated in basing head 4 moving in the direction indicated by arrow 56, is indexed into the welding station. The lead wires 11, 11 have previously been threaded through the terminals 7, 7' and bent laterally aside, either manually or through a suitable bending mechanism. The lamp engages finger 57 which atcuates safety interlock switch 58 supported by brackets 59 and 60 from inclined standard 17. Compressed air is admitted to the pneumatic air cylinder 15 and electrode block 12 begins to move downwardly. The head of screw 61 releases actuating lever 62 of interlock switch 63. The actuation of switches 58 and 63, which had previously disabled charging circuit 54, now allows charging of condenser bank 51.

As the electrode block continues moving down, grooved blade 35 of the first electrode engages projecting portion 11a of lead wire 11, initially extended out laterally from apertured boss 8 as illustrated for lead wire portion 11a in Fig. 3, and presses it down against basing head 4. Pin 39 of the second electrode enters the cavity in embossment 6 of the base and contacts the side of strip terminal 7. The first and second electrodes are adapted to engage the appropriate base parts before the electrode block reaches its limit of downward movement and the excess motion is absorbed by compression of springs 37 and 42 backing up the electrodes. Before the limit of downward movement is reached, third electrode 45 comes into engagement with lead wire portion 11a immedately above apertured boss 8 of strip terminal 7. As soon as contact is made, condenser bank 51 begins to discharge and part of the current flow is through lead wire portion 11a to first electrode 35. The lead portion 11a melts at the contact with electrode 45 and forms into a molten ball 11b which draws back from the electrode. Thereafter current flow continues through the junction of apertured boss 8 and lead wire 11, and through terminal strip 7 to second electrode 39. The metal of the boss and wire melt away from the electrode and an arc forms in the intervening gap which causes the heat to be concentrated at the boss. The are is extinguished by the discharge of the capacitor bank and then the melt cools and fuses together into a welded juncture. The rate of lowering of the electrode block is made less than the rate of melt back of the boss and wire in order to avoid the need for accurate positioning and limit stops.

After completion of the welding operation, the electrode holder is drawn up by releasing air from the pneumatic cylinder 15. An air blast may be used to blow aside the severed portion 11a of the lead wire or else it may be brushed aside. The lamp may now be indexed to a second welding station where a similar welding mechanism may be used to sever and weld the second lead wire 11' to terminal strip 7.

Figs. 5 and 6 illustrate a variant of the invention specifically adapted for the welding of large single pin fluorescent lamp bases. These bases are used on certain types of fluorescent lamps where the electrodes are not preheated at starting, for instance on instant start lamps. As illustrated, lamp 1 is provided with a base 65 having a single large central pin 66. At the center or tip of the pin there is provided an apertured boss or teat 67 through which both lead-in wires 68 are drawn.

The electrode holder or block 69 is provided with a first electrode in the form of a spring loaded shoe 71 which engages the laterally projecting leads 68 and presses them down against the basing head 4. The second electrode consists of a pair of springy blades 72 which engage the side of pin 66 as best seen in Fig. 6. The third electrode comprises a Wheel 73 provided with a plurality of electrode pins 74. The electrode wheel is mounted for rotation on a shaft 75 and a spring loaded detent ball 76 holds the wheel with an electrode pin in place for engaging leads 68 where they emerge through apertured boss 67 of the base pin. After each welding operation the electrode wheel is indexed one position to bring the next electrode pin into place for use. The indexing is done through a ratchet 77 on the lower end of rod 78 which engages a toothed wheel 79 fast on shaft 75. The upper end of the rod is pivotally fixed at 80 and the motion of the electrode block relative to the arm during the upstroke causes the operation of the ratchet. A revolving brush 81 is provided which engages one of the electrode pins while the electrode block is raised and brushes off the oxide which forms during welding. The electrode holder 69 is suspended from rod 13 through an intermediate spring loaded rod 13 for taking up excess motion, and through block 31 fastened to the lower end of rod 13.

The welding mechanism of Figs. 5 and 6 operates in generally the same fashion as that previously described. The electrode block is lowered by pneumatic cylinder 15 which actuates slide rod 13. The first electrode shoe 71 and second electrode plates 72 initially engage leads 68 and pin 66 respectively. Before the limit of downward movement, electrode pin 74 contacts leads 68 at the point where they emerge from the apertured boss in the end of pin 66. The initial current through the projecting lead portions to the first electrode severs those portions, and then the remaining current to the second electrode causes the ends of the leads and the apertured boss 67 to melt and fuse together into a welded juncture.

While the process of the invention and specific mechanisms for carrying it out have been described in detail by reference to preferred embodiments, these are intended as exemplary. The process of the invention can readily be adapted to welding lead wires to other terminal configurations. For instance, by suitable modification of the contacting blades 72, the mechanism of Figs. and 6 may be used for welding narrow pins of the kind commonly used with bi-pin fluorescent lamp bases. The scope of the invention is therefore not to be limited to specific details which have been described except insofar as included in the appended claims.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. The method of welding a lead wire to an apertured metal terminal of an electric lamp base through which the lead projects, which comprises the steps of engaging the projecting portion of the lead by a first electrode, engaging the terminal by a second electrode, moving a third electrode into contact with said lead next said aperture, and discharging a charged capacitor between said electrodes so that current from said third electrode divides and part flows through said projecting lead portion to said first electrode and melts said projecting lead portion away from the aperture, and part flows through the lead and terminal about said aperture to said second electrode and causes the lead to melt and fuse into a welded juncture with the terminal at said aperture.

2. The method of welding a lead wire to a metal terminal of an electric lamp base having an apertured boss through which the lead emerges and from which it projects laterally, which comprises the steps of engaging the projecting portion of the lead at a point removed from the aperture by a first electrode, engaging the terminal by a second electrode, moving a third electrode into contact with said lead immediately above said aperture, and discharging a charged capacitor between said electrodes so that current from said third electrode divides and part flows through said projecting lead portion to said first electrode and melts said projecting lead portion away from the aperture, and part flows through the lead and apertured boss to said second electrode and causes the lead wire and boss to melt and fuse together into a welded juncture.

3. The method of welding a lead Wire to a metal terminal of an electric lamp base having an ape-rtured boss through which the lead projects, which comprises the steps of bending the projecting portion of the lead aside from the aperture, engaging the projecting portion of the lead at a point removed from said aperture by a first electrode, engaging the terminal by a second electrode, moving a third electrode into contact with said wire immediately above said aperture, and discharging a charged capacitor between said third electrode and said first and second electrodes so that current from said third electrode divides and part flows through said projecting lead portion to said first electrode and melts said projecting lead portion away from the aperture, and part flows through the lead and apertured boss to said second electrode and causes the lead wire and boss to melt and fuse together into a welded juncture.

4. Apparatus for welding the lead wires of an electric lamp to the confined strip terminals of a recessed double contact base, said strip terminals having apertured bosses through which the lead wires project, comprising a basing head for holding said lamp and base, and a welding mechanism including an electrode holder having a first electrode adapted to engage the projecting portion of the lead wire, a second electrode adapted to engage the strip terminal, and a third electrode for contacting the lead wire at the point of emergence from said apertured boss, means for moving said electrode holder towards said base so that said first and second electrodes engage said projecting lead portion and said strip terminal respectively and said third electrode contacts said lead wire, and a charged capacitor connected to said electrodes and pro viding current flow from said third to said first electrode to sever said projecting lead portion, and from said third to said second electrode to melt the end of the lead wire together with the apertured boss whereby to form a welded juncture.

5. Apparatus for welding the lead wires of an electric lamp to the confined strip terminals of a recessed double contact base, said strip terminals lining the side walls of a central passage in a. projecting embossment of said base and having laterally extending upper portions provided with apertured bosses through which the lead wires project, comprising a basing head for holding said lamp and base, and a welding mechanism including an electrode holder having a first electrode adapted to engage the laterally projecting portion of the lead wire, a second electrode adapted to penetrate into said passage and engage said strip terminal, and a third electrode for contacting the lead wire at the point of emergence from said apertured boss, means for moving said electrode holder towards said base so that said first electrode engages said projecting lead portion, said second electrode penetrates into said passage and engages said strip terminal, and said third electrode contacts said lead wire before the limit of movement of said electrode holder, and a. charged capacitor connected to said electrodes and providing current flow from said third to said first electrode to sever said projecting lead portion and from said third to said second electrode to melt the end of the lead wire together with the apertured boss whereby to form a welded juncture.

6. Apparatus for welding a lead wire of an electric lamp to the 'apertured pin terminal of a base through which the lead wire emerges and from which it projects laterally, comprising a basing head for holding said lamp and base, and a welding mechanism including an electrode holder having a first electrode adapted to engage the projecting portion of said lead wire, a second electrode adapted to engage said pin terminal, and a third electrode for contacting the lead wire at the point of emergence from said pin, means for moving said elec trode holder towards said base so that said first electrode engages said projecting lead portion, said second electrode engages the side of said pin, and said third electrode contacts said lead wire before the limit of movement of said electrode holder, and a charged capacitor connected to said electrodes and providing current flow from said third to said first electrode to sever said projecting lead portion and from said third to said second electrode to melt the end of the lead wire together with the pin about the aperture whereby to form a welded juncture.

7. The apparatus of claim 6 including an indexing wheel mounted on said electrode holder and carrying a plurality of electrode rods, and means for indexing said wheel at successive welding operations in order to present a new electrode rod to serve as said third electrode for each welding operation.

References Cited in the file of this patent UNITED STATES PATENTS 2,749,528 Albrecht June 5, 1956 

